The present invention relates to a tool changing arrangement for a machine tool comprising an axially advanceable drive spindle provided with a holding member having a receiving part into which a tool carrier may be pushed laterally and be held thereon substantially coaxial with the spindle, and in which the drive spindle and the tool carrier are provided at facing ends thereof with centralizing parts which, during the coupling of the two members and relative movement between the drive spindle and the holding member axially align the drive spindle and the tool carrier. The arrangement includes further parts for transmitting a turning moment from the drive spindle to the tool carrier.
In a known arrangement of the aforementioned kind, the holding member is in the form of tongs located outside the spindle and movable with the same in axial direction, but not turnable relative thereto. The tool carrier must therefore be supported in a special way with respect to the holding member. The tool carrier is provided with a steep cone extending into a corresponding internal conical surface of the drive spindle to axially align these two elements with respect to each other. In order to transmit a turning moment from the spindle to the tool carrier, the spindle has to be provided with separate elements which enter into the steep cone of the tool carrier. Wear of the inter-engaging elements is thereby unavoidable, which will lead to an undesired chatter of the tool carrier and the tool carried thereby. The holding member located outside of the spindle, and hydraulically moved in axial direction relative thereto, requires considerable space and is necessarily complicated in construction. The steep cone requires a large stroke for engagement with the internal cone surface and the interengaging surfaces have to be manufactured to very close tolerances, while still not providing a perfect axial alignment of the two members. Furthermore, each tool carrier requires an expensive bearing. The tool carriers form with different tools respectively a unit, which during machining of a workpiece must usually be changed several times.